If your property has an EPC rating of band G, it's the lowest energy efficiency rating a home can receive — but that also means there's significant room for improvement, and even modest upgrades can make a real difference.
Moving from G to F is often very achievable, because many G-rated homes are missing basic energy efficiency measures that are relatively inexpensive to install.
This guide covers:
- what EPC band G actually means (and how far you are from F)
- the cheapest upgrades that typically deliver the biggest point gains for G-rated homes
- medium-cost improvements for homes that need more work
- typical costs and a summary comparison table
- government grants — G-rated homes are often the highest priority for funded upgrades
- what landlords must know about minimum energy standards
If you want to see the EPC for your specific address (plus recommended improvements), you can check it by postcode on EPC Advisor: Check your EPC by postcode
Understanding your G rating
An EPC rating is based on a points score (often called the SAP score on domestic EPCs). The bands work like this:
- Band G = 1–20 points
- Band F = 21–38 points
To move from G to F, you need your property to reach at least 21 points.
What typically causes a G rating?
Band G homes usually have several serious energy efficiency problems at once. Common causes include:
- No insulation at all — no loft insulation, uninsulated walls, and no floor insulation
- Old, inefficient heating — outdated electric storage heaters, very old boilers, or no central heating system
- Single glazing throughout the property
- No heating controls — no programmer, no room thermostat, no TRVs
- Solid walls without insulation — common in older properties built before the 1920s
- Uninsulated hot water cylinder — or no cylinder jacket
G-rated homes often have a combination of these issues. The good news is that because so many basic measures are missing, even straightforward improvements can deliver a large points gain.
Step 1: Check your current score (how close are you to F?)
On your EPC certificate (the first page), you'll usually see:
- your current rating (G)
- a number next to it (your points score)
- a table of recommended measures, with a predicted rating after each improvement
That recommendations table is your best friend when planning upgrades — it shows which measures the assessor expects to move the rating.
The maths is simple:
Points needed to reach band F = 21 − your current EPC score
Examples:
- EPC G18 → you need +3 points
- EPC G14 → you need +7 points
- EPC G8 → you need +13 points
If you're already at 15–20 points, a couple of cheap improvements may be enough. If you're well below 15, you'll likely need a combination of low-cost and medium-cost measures.
If you don't have your certificate handy, you can look it up by postcode: Find your EPC report
Step 2: Start with the cheapest improvements
These upgrades are low-cost, low-disruption, and can often be completed quickly. For G-rated homes that are missing basic measures, these tend to deliver strong EPC point gains.
1) Loft insulation (if missing or very thin)
Typical cost: £300–£600 (for installing up to 270mm where none exists) Expected EPC gain: 5–15 points
This is often the single most impactful upgrade for a G-rated home. If your loft has no insulation at all — or just a thin, patchy layer — installing mineral wool insulation to the recommended 270mm depth can deliver a huge improvement.
Practical tips:
- If there's existing insulation that's very thin (under 100mm), topping up is cheaper than starting from scratch.
- Don't compress insulation under stored items — it reduces performance.
- Insulate the loft hatch and any exposed pipework in the loft for extra benefit.
- If your home has a flat roof or a room-in-roof (converted loft), the approach and cost will be different.
Want a deeper dive? Does loft insulation improve your EPC rating?
2) Hot water cylinder jacket
Typical cost: £20–£50 for an 80mm jacket Expected EPC gain: 1–3 points
If you have an uninsulated hot water cylinder, adding a jacket is one of the cheapest energy upgrades available. It's usually a DIY job and takes minutes to fit. EPCs specifically record whether the cylinder is insulated, so this is a straightforward win.
3) Draught proofing
Typical cost: £100–£300 (DIY is cheaper; professional whole-house draught proofing costs more) Expected EPC gain: 1–3 points
G-rated homes often have significant uncontrolled air leakage. Common wins include:
- external doors (seals, brush strips, letterbox brushes)
- sash windows (brush strips)
- gaps around pipework
- unused chimney (temporary draught excluder when not in use)
Important:
- Don't block deliberate ventilation (air bricks, extractor fans, trickle vents).
- If you have an open-flued appliance or open fire, get professional advice before sealing gaps.
4) LED lighting
Typical cost: £50–£200 (depending on number of fittings) Expected EPC gain: 1–3 points
EPCs record the proportion of fixed low-energy lighting in the home. If your property still uses old incandescent or halogen bulbs, switching to LED is cheap and easy.
Practical tips:
- Prioritise fixed fittings (ceiling lights, downlights, integrated units) — these are what the EPC assessor counts.
- Replace old halogen spotlights with LED versions if possible.
5) Heating controls (TRVs, programmer, thermostat)
Typical cost: £200–£500 (varies by system and installer) Expected EPC gain: 3–8 points
Many G-rated homes have no heating controls at all, or only very basic ones. EPCs score heating controls and system management, so adding missing controls can deliver a meaningful improvement.
Controls that often help:
- programmer / timer
- room thermostat
- thermostatic radiator valves (TRVs)
If your EPC already lists missing controls as a recommendation, it's a strong sign they'll help your rating.
Step 3: Medium-cost improvements (for homes further from F)
If your score is very low (under 10–12 points), the quick wins above may not be enough on their own. You'll likely need one or more of these medium-cost measures.
1) Cavity wall insulation
Typical cost: £800–£1,500 depending on property size and access Expected EPC gain: 5–15 points
If your home has unfilled cavity walls, this can be one of the highest-impact upgrades available. Many G-rated homes from the 1930s–1970s have cavity walls that were never insulated.
However, cavity wall insulation isn't suitable for every property. It may not be appropriate if your home is:
- highly exposed to wind-driven rain
- in poor external condition (pointing/gutters/brickwork issues)
- flood-prone
- built with narrow cavities
Before installation:
- fix any external maintenance issues first (pointing, gutters, cracks)
- use a reputable installer with appropriate guarantees
If your EPC states "solid wall" rather than "cavity wall", this measure won't apply — see the section on harder cases below.
2) Replacing old electric heaters with storage heaters or gas central heating
Typical cost: £2,000–£5,000 depending on system type and property size Expected EPC gain: 10–30 points
Many G-rated homes have outdated or inefficient electric heating — old panel heaters, ancient storage heaters, or no proper heating system at all. Upgrading the heating system can deliver the largest single EPC improvement of any measure.
Possible routes:
- Modern high heat-retention storage heaters — cheaper than a full system change, and often a big improvement over old models
- Gas central heating — if a gas supply is available, installing a condensing boiler with radiators can transform the EPC
- Heat pump — consider this if you can access grant funding and improve insulation first
If you're exploring heat pumps, look into the Boiler Upgrade Scheme (England & Wales) — it offers a grant towards eligible installations.
3) Double glazing (if the property has single glazing)
Typical cost: £3,000–£7,000 depending on number and size of windows Expected EPC gain: 3–8 points
Single glazing is common in G-rated homes and contributes to both heat loss and a poor EPC score. Replacing single-glazed windows with modern double glazing improves thermal performance and reduces draughts.
This is a significant investment, and the EPC point gain per pound spent is lower than insulation or heating upgrades. It's often worth prioritising insulation and heating first, then considering glazing if you still need more points — or if the windows need replacing anyway.
Cost summary table
| Improvement | Typical cost | Expected EPC gain |
|---|---|---|
| Hot water cylinder jacket | £20–£50 | 1–3 points |
| LED lighting | £50–£200 | 1–3 points |
| Draught proofing | £100–£300 | 1–3 points |
| Heating controls (TRVs, programmer, thermostat) | £200–£500 | 3–8 points |
| Loft insulation (none → 270mm) | £300–£600 | 5–15 points |
| Cavity wall insulation | £800–£1,500 | 5–15 points |
| Replacing old electric heaters | £2,000–£5,000 | 10–30 points |
| Double glazing (replacing single) | £3,000–£7,000 | 3–8 points |
The right combination depends on your current score and what measures your EPC recommends. Start with the cheapest wins and work down the table until you've gained enough points to cross into band F.
For a broader overview of cost-effective improvements across all bands: Cheapest ways to improve your EPC rating
Government grants and funding
G-rated homes are often the highest priority for government-funded energy efficiency schemes. If your home is band G, you may qualify for fully-funded or heavily subsidised upgrades — so it's worth checking before you spend your own money.
ECO4 (Energy Company Obligation)
The ECO4 scheme is funded by energy suppliers and targets the least efficient homes. G-rated properties are the highest priority band under ECO4. Eligible households can receive:
- free loft insulation
- free cavity wall insulation
- heating system upgrades
- in some cases, solid wall insulation or solar panels
Eligibility typically depends on your household income, benefits status, and property rating. Contact your energy supplier or local authority to check.
Great British Insulation Scheme (now closed)
This scheme targeted low-rated homes and provided funded insulation measures (particularly cavity wall and loft insulation) for eligible properties. GBIS closed to new applications on 31 January 2026 and the scheme ends 31 March 2026.
Warm Homes Plan
The government's Warm Homes Plan aims to help homeowners upgrade the energy performance of their properties with support for insulation and low-carbon heating. Check current eligibility and available measures.
Because schemes and eligibility change, the best approach is to check what's currently available: Home energy grants in the UK: what help is available?
Landlords: what you need to know about G-rated rental properties
If you're a landlord with a G-rated property, this isn't just about energy bills — it's a legal compliance issue.
Minimum Energy Efficiency Standards (MEES)
In England and Wales:
- privately rented properties must meet a minimum EPC rating of E
- a G-rated property cannot be legally let without a registered exemption
- penalties for non-compliance can reach £5,000 per property
This means that moving from G to F is a step in the right direction, but you'll ultimately need to reach band E to comply. However, reaching F first is a sensible milestone — especially if budget is tight or you're working through improvements in stages.
The cost cap and exemptions
If you cannot reach EPC E within the £3,500 cost cap (including VAT):
- you must still install all recommended measures you can up to the cap
- then register the appropriate exemption (with evidence)
For G-rated homes, you may be able to access grant funding (particularly ECO4) to cover some or all of the upgrade costs, which means the cost cap may be less of a barrier than expected.
Future requirements
The government has indicated a target of EPC band C by 2030 for rented properties. While timelines may shift, the direction is clear — landlords will need to continue improving energy performance over time.
For more detail on landlord obligations:
What to do next
- Check your current EPC score and recommendations — find out exactly how many points you need to reach band F
- Check grant eligibility first — G-rated homes are high priority for schemes like ECO4, and you may qualify for free or subsidised upgrades
- Prioritise the cheapest wins — loft insulation, cylinder jacket, lighting, heating controls
- Get the work done — use reputable installers and keep all invoices and certificates
- Book a new EPC — EPCs don't update automatically, so you'll need a fresh assessment to prove the new rating
Start here: Check your EPC rating by postcode
If you're planning further upgrades after reaching F, these guides cover the next steps: